AU753487B2

AU753487B2 - Dental cartridge having an attached delivery portion

Info

Publication number: AU753487B2
Application number: AU93281/98A
Authority: AU
Inventors: William B Dragan; Gordon Rowe
Original assignee: Centrix Inc
Current assignee: Centrix Inc
Priority date: 1997-12-02
Filing date: 1998-11-19
Publication date: 2002-10-17
Anticipated expiration: 2018-11-19
Also published as: US6135771A; EP0919206B1; AU9328198A; EP0919206A2; DE69839580D1; JPH11221234A; EP0919206A3

Description

1. FIELD OF THE INVENTION The present invention relates generally to a dental cartridge used to deliver dental material, and particularly to a cartridge having a delivery portion with a cannula that attaches 5 to the front of the cartridge.

2": .0 0000 0 OS 0 0 *0* 0 0 0 00 BACKGROUND OF THE INVENTION In dentistry, it is common to dispense different dental materials with a cartridge used in combination with a syringe.

In many applications, the dental material is required to be mixed within the cartridge, such as in the use of amalgam, cement, or glass ionomer materials. Some dental capsules may come prepackaged or premixed. Additionally, some capsules are not able to be dispensed from the capsule directly. Many prepackaged capsules are limited in the volume of material that can be mixed because of the limited amount of component materials that are prepackaged, such as a volume of liquid. A first component of a la F 0 P-2131 material is usually placed within a cartridge or capsule and mixed with a liquid component in a mechanical mixer, such as an amalgamator, prior to dispensing. While mixing these dental materials, it is required to keep the first component, which is typically a powder, from entering the delivery portion of the cartridge or capsule. The delivery portion is usually a reduced diameter cannula having a lumen or small bore therein. Problems often occur in that an unmixed portion of the first component will inadvertently enter the lumen and cause blockage. This prevents dispensing of the mixed dental material contained within the body of the cartridge. Material and time is often wasted in that the defective cartridge must be thrown away, and the process of mixing the dental material started over. This is inconvenient Sin that the patient must typically wait, after being prepared for 15 application of the dental material, until the dentist can prepare *0 another cartridge of dental material. Additionally, the dentist looses valuable productive time. Various methods have been used in an attempt to prevent unintentional blockage of the lumen with dental material before being mixed. Such solutions have been in 20 the form of pins inserted within the lumen to prevent material 0: unintentionally entering the lumen, and seals placed between the lumen and the interior body portion of a cartridge. However, these methods are often inconvenient to use and not completely P-2131 reliable. One such cartridge is disclosed in United States Patent 5,172,807 entitled "Cement Mixing Capsule" and issuing to Dragan et al on December 22, 1992, which is herein incorporated by reference. Therein disclosed is a dental cartridge or capsule having a frangible seal placed between a nozzle and the body portion of the capsule to prevent unmixed cement from entering the nozzle. Another cartridge and dental syringe is disclosed in United States Patent 5,306,147 entitled "Dental Syringe and Cartridge Therefor" issuing to Dragan et al on April 26, 1994, which is herein incorporated by reference. While these prior devices and methods have proven useful, there is a need for a more reliable and easily manufactured dental cartridge for use oooo with dental materials requiring mixing or requiring to be temporally separated from a cannula used for dispensing or 15 applying the dental material.

••go SUMMARY OF THE INVENTION Accordingly, the present invention provides in one aspect a method for mixing and dispensing a dental material V including the steps of: "20 preloading a predetermined amount of a dental material into a dispensing cartridge having a filling end and an opposite discharge and closed by a frangible seal, sealing the filling end of the dispensing cartridge with a displaceable piston after the filling thereof with said material, storing the cartridge containing said preloaded dental material until ready for use, removing the displaceable piston prior to using, placing a predetermined amount of a second dental material into said cartridge to be mixed with said first dental material whereby the user may selectively adjust the ratio of said first and second dental materials, replacing the displaceable piston to reseal said filling end of the cartridge, agitating said cartridge to mix said first and second dental materials in situ within said cartridge to form a homogeneous mixture of said first and second materials, fracturing said frangible seal, and effecting the displacement of said piston to extrude the 15 homogeneous mixture of said first and second dental materials through said discharge end directly where needed.

In accordance with a second aspect of the invention there is provided a dispensing cartridge for practising the method for mixing and dispensing a dental material described above, 20 wherein the cartridge includes: a body defining a reservoir for receiving a dental material to be dispensed, said body having an open filling end and an oppositely disposed discharge end, said discharge end defining a discharge opening, means forming a frangible seal to seal said discharge opening, a displaceable piston to seal said filling end, said piston having an ear to facilitate grasping said piston for effecting the removal and reinsertion of said piston.

The present invention is a dental cartridge for dispensing a dental material with a delivery portion having a cannula that snaps onto a reduced diameter end of the cartridge. A frangible seal is placed adjacent or within the reduced diameter end of the cartridge separating the reduced diameter end from the larger body portion of the cartridge.

A delivery portion or cap having a *S S.

0 0 o: oo oo P-2131 cannula fixed therein snaps onto the reduced diameter portion.

The cannula extends sufficiently far to enter the reduced diameter portion of the cartridge and puncture the frangible seal therein. In another embodiment a twist-off tab is used as a frangible seal. In one embodiment, the delivery portion or cap is securely held onto the reduced diameter end of the cartridge by a snap fit locking mechanism. Flow between the body portion of the cartridge and the cannula in the delivery portion or cap is thereby securely established. A plug having flexible ears or handles thereon is inserted into the back end of the cartridge to force the material out of the cartridge and through the lumen of the cannula for application of the mixed dental material to the patient. The plug may be advanced by any convenient dispensing device, such as a syringe or other mechanical applicator.

o S 15 Accordingly, it is an object of the present invention to provide a cartridge with a seal that will break or rupture only when intended.

.It is a further object of the present invention to permit mixing of a dental material without unintentionally blocking or 20 clogging the delivery end of the cartridge or cannula.

It is an advantage of the present invention that a metal cannula may be used permitting bending to facilitate placement of the dental material.

I.

P-2131 It is a further advantage of the present invention that the dentist may select different sized cannulas to be used in combination with a single dental cartridge.

It is a feature of the present invention that the dispensing cannula is used to break a frangible seal.

It is another feature of the present invention that a twistoff tab provides a frangible seal.

It is a further feature of the present invention that the plug or piston used with the cartridge has flexible ears for grasping.

It is a further feature of an embodiment of the present invention that the delivery portion or cap snaps onto a reduced diameter end of the cartridge body.

6e 6 These and other objects, advantages, and features will S 15 become readily apparent in view of the following more detailed 6066 description.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an embodiment of the present o oo invention.

20 Fig. 2 is a perspective view of a plug.

6660 Fig. 3 is a perspective view of a delivery portion or cap.

.:ago: Fig. 4 is a partial cross section and exploded view of a Fig. 4 is a partial cross section and exploded view of a .1 I 1.

P-2131 front portion of the present invention.

Fig. 5 is a cross section taken along line 5-5 in Fig. 4.

Fig. 6 is a longitudinal cross section of an embodiment of the present invention.

Fig. 7 is a cross section of a portion of an embodiment of the present invention.

Fig. 8 is a cross section taken along line 8-8 in Fig. 7.

Fig. 9 schematically illustrates another embodiment of the present invention without a delivery portion placed thereon.

Fig. 10 schematically illustrates the embodiment illustrated in Fig. 9 with a delivery portion placed thereon.

Fig. 11 is a perspective view illustrating another .o embodiment.

Fig. 12 is a partial cross section of the embodiment S. Se illustrated in Fig. 11.

*050 5 S° Fig. 13 is a partial side view illustrating the front portion of another embodiment of the present invention.

Fig. 14 is a front view of the embodiment illustrated in Fig. 13.

oo S 20 Fig. 15 is a partial side view illustrating the front ee portion of the embodiment illustrated in Figs. 13 and 14 adapted *°°00 to receive a threaded delivery portion.

Fig. 16 is a partial side view illustrating the front P-2131 portion of the embodiment illustrated in Figs. 13 and 14 adapted to receive a delivery portion having a flange.

Fig. 17 is a partial side view illustrating the front portion of another embodiment of the present invention.

Fig. 18 is a partial cross section illustrating the embodiment illustrated in Fig. 17 with a delivery portion attached.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 generally illustrates an embodiment of the present invention. A dental cartridge is comprised of a body 10 having a holding or collar end portion 12 and a delivery portion or cap 16. The dental cartridge may be made of any suitable material, for example plastic. Held within delivery portion or cap 16 is tube or cannula 18. The cannula 18 may be held with friction or sealed or glued in place. Sealing the larger diameter open end of body 10 is a piston or plug 14. Typically, material is placed within the body 10 of the cartridge and mixed prior to placement of the delivery portion or cap 16 on the other end of the body The material, which is preferably dental material, is then dispensed through the cannula 18. The cannula 18 is preferably made from metal that is easily bent, but may be made from any material.

P-2131 Fig. 2 more clearly illustrates the piston or plug 14 illustrated in Fig. 1. The-piston or plug 14 is comprised of a generally cylindrical body having handles or ears 20 formed on one end. The handles or ears 20 are flexible and facilitate grasping or holding of the plug 14 for insertion and removal permitting easy filling of the cartridge with material. The handles or ears 20 extend radially beyond the generally cylindrical body of the plug 14. Additionally, the ears 20, being flexible, bend backwards and do not interfere with the advancing motion of the plug 14 when pushed through the body 10 of the cartridge by a syringe or other mechanical applicator, not shown.

~The plug 14 also has a front wipe 22 and a rear wipe 24 with an 0 r° intermediate portion 26 therebetween.

Fig. 3 more clearly illustrates the delivery portion or cap 15 16 illustrated in Fig. 1. However, Fig. 3 illustrates the 0 delivery portion or cap without the cannula 18 inserted. The interior space of delivery portion or cap 16 has a plurality of ramps 30 equidistantly spaced therein. A flange 28 provides a *0 grasping area to facilitate pushing the delivery portion or cap ~e

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20 16 onto the cartridge body 10. The reduced cap portion 32 is sized to retain the cannula 18, shown in Fig. 1.

Fig. 4 more clearly illustrates the front end portion of the cartridge. The cartridge body 10 has a reduced diameter portion 38 with a locking means formed thereon. The locking means may have any structure capable of locking or firmly holding on to a delivery portion or cap 16. By way of example, the locking means comprises an angled surface 34 and an exterior shoulder 36. The delivery nozzle, portion or cap 16 has ramps 30 therein that have an interior shoulder 33 that is adapted to mate with exterior shoulder 36. Preferably, there are four ramps equally spaced around the inside diameter of the delivery portion or cap 16. Cap, nozzle or delivery portion 16 has a flange 28 thereon. The flange 28 facilitates holding of the delivery portion nozzle, or cap 16 and placement onto the cartridge body 10. One end of the cap 16 has a go o reduced diameter cap portion 32. The reduced diameter cap portion o 32 has a' bore 44 therein. The bore 44 is sized to frictionally 15 receive and hold securely the cannula 18. Cannula 18 may be made of any material, but-is preferably made of a bendable metal material, such as a soft stainless steel. Openings or vents 42 are placed within the delivery portion or cap 16 and help to ~prevent entrapping air upon placement of the cap 16 onto the 20 cartridge body 10. Additionally, openings 42 are helpful in the eeoc molding process. A frangible diaphragm 40 seals theopening within the reduced portion 38. The frangible diaphragm prevents dental material 60 from being dispensed from the cartridge until the frangible diaphragm 40 is ruptured. After P-2131 preparation or mixing of the dental material 60 contained within the body 10 of the cartridge, the delivery portion or cap 16 is moved in the direction of arrows 46 to become locked with a snap fit onto the end of the body 10. The ramps 30 are caused to slide over the angled surface 34 and when fully positioned, the internal shoulder 33 mates with the external shoulder 36, securely holding the delivery portion or cap 16 onto the reduced diameter portion 38 of the body 10. A portion of the cannula 18 extends within the interior of the delivery portion or cap 16 sufficiently far so as to strike the frangible diaphragm causing it to rupture. The end of the cannula 18 then extends ooooo into the body 10 of the cartridge, permitting the prepared dental S. material 60 to flow therein. Angled surface 34 seals the opening 42.

15 Fig. S is a cross section taken along line 5-5 in Fig. 4.

Fig. 5 more clearly illustrates an embodiment of the diaphragm e* 40. Diaphragm 40 comprises a thin wall or seal which effectively 0000 prevents dental material from escaping or traveling out of the cartridge body. Scored or reduced thickness sections 48 help to ooo o 20 provide a weakened portion for more easily rupturing the frangible diaphragm 40 with the cannula. The scored or reduced 0 thickness sections 48 circumscribe the frangible diaphragm with the diaphragm 40 comprised of two sections. Each section is P-2131 attached to the reduced diameter portion 38 by a hinge 50. The hinges 50 prevent the frangible diaphragm 40 from breaking free and mixing with the dental material contained within the body of the cartridge. While this embodiment is illustrated with two sections, clearly any number of sections may be provided.

SFig. 6 illustrates an embodiment of the present invention in assembled form. The end portion or holding collar 12 has a front shoulder 52 and a rear shoulder 54 forming a groove or channel 64: Typically, a holding device is placed within the groove 64 to hold the cartridge body 10 in position while a plunger, not shown, is advanced to contact the back of the plug **Ss or piston 14. For example, the cartridge body 10 may be placed in a syringe or applicator device such as that disclosed in U.S.

Patent 5,306,147 entitled "Dental Syringe and Cartridge 15Therefor", which is herein incorporated by reference. The plug or piston 14 is advanced in the direction of arrow 66 so as to extrude the material 60 contained within the body 10 of the cartridge. A vent 15 is placed in a portion of the body 10 so that air is permitted to escape as the plug or piston 14 is 20advanced into the body 10. Alternately, the vent may be molded into the plug or piston 14. The delivery portion or cap 16 being 0.

snapped into position on the front reduced diameter portion 38 of the body 10 is securely held in position by the mating shoulders P-2131 33 and 36 of the ramps 30 and angled surface 34. The end of the cannula 18, placed within the delivery portion or cap 16 has a sufficient length to break or pierce the frangible diaphragm Accordingly, by placement of the delivery portion or cap 16 on the reduced diameter portion 38 of the cartridge body 10, the breaking or rupturing of the frangible diaphragm 40 is assured.

As the plug or piston 14 is advanced, dental material 60 is extruded through the bore or lumen 56 of the cannula 18, to be delivered, typically into a patient's prepared tooth. The front surface 58 of the plug 14 may be formed to compliment the front body surface 62. In this way, nearly all of the dental material ses*: 60 contained within the cartridge is extruded, resulting in very little waste.

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o. Fig. 7 illustrates another embodiment of the present 15 invention. In Fig. 7, only a portion of the body 110-is illustrated for convenience. The reduced diameter portion 138 has o. a frangible diaphragm or seal 140 therein. The front portion of the reduced diameter portion 138 has an exterior angled surface 134 and an interior angled surface 135. The interior angled 20 surface 135 facilitates and guides the placement of the cannula 118. Cannula 118 also has a bore or lumen 156. A shoulder 136 is formed at one end of the exterior angled surface 134. A complimentary mating shoulder is formed on a delivery portion or P-2131 cap similar to that illustrated in the previous figures, however, for convenience this is not illustrated in Fig. 7.

Fig. 8 more clearly illustrates the frangible diaphragm or seal 140, illustrated in Fig. 7. Fig. 8 is a cross section taken along lines 8-8 in Fig. 7. In this embodiment, the frangible diaphragm or seal 140 is formed by a scored or reduced thickness portion 148 circumscribing a substantial portion of the frangible diaphragm 140. A land or hinge 150 is used to secure the frangible diaphragm 140 to the reduced diameter portion 138 when the scored or reduced thickness section 148 is ruptured or broken by the cannula 118, illustrated in Fig. 7.

**ego: 0 Fig. 9 and 10 illustrate another embodiment of the present °O invention. In this embodiment a twist-off tab forms a frangible 00 o :0.0 seal or diaphragm which is associated with a reduced diameter end o oo 15 of a cartridge or capsule. Referring to Fig. 9, a body portion 0@ S 210 is adapted to receive a material to be mixed. One end of the body portion 210 has a relatively large opening at one end to receive a plug or piston, not shown in Fig 9. A longitudinal vent 215 is placed in the body portion 210. The vent 215 extends only 0 20 partially along the length of the body portion 210. Near or 0 adjacent the relatively large opening is a holding portion or •0 e collar 212. The holding portion 212 is adapted to be received by any conventional delivery system, such as a syringe. The other any conventional delivery system, such as a syringe. The other P-2131 end of the body portion 210 has a reduced diameter end or portion 238. The reduced diameter end or portion 238 has a passage therein. The passage has a narrowed diameter portion 237 intermediate either end of the passage. On one end of the passage is a rear passage opening having an angled surface 239. On the other end of the passage is a front p~e9eage opening having an angled surface 235. Associated with the reduced diameter portion 238 is a tab 266. Tab 226 provides a frangible diaphragm or seal 240 to the passage formed by angled surfaces -239 and 235, and seals the passage in the reduced diameter portion 328. The thin walled section 241 permits the tab 226 to be twisted off, broken away, or removed from the reduced diameter portion 238 providing an opening to the passage formed by angled surfaces 239 and 235.

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An angled surface 234 is formed on the reduced diameter portion e 15238. At the rear portion of the angled surface 234 is an external shoulder 236.

Fig 10 schematically illustrates the cartridge or capsule •e with the twist-off tab 226, illustrated in Fig. 9, removed and a delivery portion 216 attached. The delivery portion 216 is ee••• ~20 similar to the delivery portion illustrated in the prior figures, and is generally made of plastic with a bendable cannula 218 o. S placed there through. The cannula 218 is preferably made of metal, but also may be made of plastic or other similar material.

P-2131 A rear portion of the cannula 218 is guided by the angled surface 235 through the passage formed thereby and communicates with or extends into the body portion 210. The narrowed diameter portion 237 holds and seals around the cannula 218. The delivery portion 216 is pushed or snap-fit onto the reduced diameter end or portion 238. Flange 228 helps in grasping the delivery portion 216. An internal shoulder 233 formed on the delivery portion mates with the external shoulder 236 formed on the reduced diameter end or portion 238 thereby effecting a snap-fit securely holding the delivery portion onto the body portion 210. A plug 214 is inserted into the relatively large rear opening of the o••oe body portion 210. The plug 220 has a plurality of flexible ears or handles 220 that assist in grasping and inserting the plug 214 into the body portion 210. The material 260 within the body 15 portion 210 can be dispensed or extruded by advancing the piston or plug 214 with any conventional applicator, such as a syringe, not shown.

0S00 S.The operation of this embodiment is readily appreciated with reference to Figs. 9 and 10. A material, preferably a dental .20 material 260, is placed within the body portion 210. The tab 266 forms a frangible diaphragm or seal 240 associated with the reduced diameter end 238 preventing material from escaping from the body portion 210. A plug 214 is inserted into the relatively P-2131 large opening adjacent the holding portion 212 and the material is mixed, if mixing is required. After mixing, tab 266 is removed. The rear end of cannula 218 in the delivery portion 216 is then placed in the passage formed by angled surfaces 239 and 235. The delivery portion is securely held onto the body portion 210 with the complementary or mating internal shoulder 233 and external shoulder 236. The cartridge is then placed in a dispenser or syringe and the material 260 may then be dispensed or extruded providing accurate and precise placement.

Fig. 12 and 13 illustrate another embodiment of the present invention. The dental cartridge in this embodiment has a body 310 000000 with a holding or collar portion 312 and an initially closed

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front portion. The front portion comprises a socket 352 having an internal thread 350 and a frangible nose or tab 366 forming a 15 closed end. The nose or tab 366 has a reduced wall thickness intermediate either end. The nose or tab 366 can be either broken or cut off forming a frangible seal permitting the opening of the 0000 closed end. Fig. 12 illustrates the placement of a delivery portion 316 on the front end of the body 310 forming a complete 20dental cartridge. The delivery portion has a cannula 318 on one end and has a thread 354 on the other end configured to mate with o0 0 the thread 350 formed within the socket 352. The body portion 310 may have a longitudinal vent 315 formed on the inside of the body P-2131 portion 310 to facilitate the insertion of a plug, not shown.

Figs. 13-16 illustrates another embodiment of the present invention. Fig. 13 illustrates the front end of a body portion 410. The front end has opposing hooks 428. The opposing hooks 428 have a inner shoulder 433. The opposing hooks 428 are formed around a reduced cylindrical portion 438. At the end of the reduced cylindrical portion 438 a tab 466 is formed initially closing or sealing the end. Intermediate between the reduced cylindrical portion 438 and the tab 466 is a reduced wall 441. The reduced wall thickness 441 permits easy removal of the tab 466 so that the front end can be opened. Fig.

000000 14 is a front end view that better illustrates the opposing hooks 428. Fig. 15 illustrates the placement of a delivery portion 316 0. o 00 :0.00* on the front end of the body 410. The delivery portion 316 has a 15cannula 318 and threads. The delivery portion 316 is the same as the delivery portion illustrated in Fig. 12. Fig. 16 illustrates the placement of another type of delivery portion 416 on the 0000 front end of the body 410. The delivery portion 410 has an open o: nozzle 418 on one end and a flange 419 on the other end. The 2 0 flange 419 is held by the opposing hooks 428. Accordingly, the front end of body 410 is adapted to hold a variety of different delivery portions 316 and 416.

Figs. 17 and 18 illustrates another embodiment of the P-2131 present invention. In this embodiment a delivery portion 516 is held by friction onto the front end of body 510. Body 510 has a reduced cylindrical portion 538 with a closed nose or tab 566 having an intermediate reduced wall thickness 541. As illustrated in Fig. 18, after removal of the closed nose or tab 566 the delivery portion 516 is forced onto the reduced cylindrical portion 538 permitting dispensing of a dental material, not shown, from the nozzle 518.

Accordingly, it should be appreciated that the present invention, in providing a cartridge that has a snap on or pop on delivery portion or cap, clearly advances the art in delivering dental material. By permitting the dentist to control and vary the amount of liquid to be mixed with a powder, the volume of 00 material may be increased over existing capsules. Additionally, 15the viscosity of the material may be easily adjusted by the 0 dentist. The delivery portion or cap may come in a variety of 00 different sized cannulas such that the dentist can choose a 00000*e particular sized cannula having a particular diameter bore or lumen to be placed on a common cartridge body. This is 20particularly advantageous in that it permits the dentist to mix ooo. or prepare dental material to a desired viscosity or consistency 4.

for a particular application. Accordingly, the dentist need not compromise the desired viscosity for use in a particular P-2131 application because of a limitation of available cannula sizes.

The different delivery portions or caps may even be color coded to identify and distinguish the different diameter cannula sizes available. Additionally, different lengths of cannula may be used and selected by the dentist, depending upon application. Further, by providing a cannula extending into the interior space of the delivery portion or cap and using the cannula for rupturing the diaphragm, the rupturing of the diaphragm is assured. Therefore, the diaphragm may be made sufficiently strong so as to avoid any unintentional rupturing and spillage of the dental material prior to being prepared or mixed. The plug facilitates insertion and e o.

removal so that the dentist can conveniently prepare the dental S"material. Typically, a powder is initially placed within the e4 4 cartridge body and the dental material is prepared by removing 15 the cap or plug and inserting a liquid catalyst within the 4.

cartridge body. The cap or plug is then replaced during mixing.

The cartridge body is placed into a mechanical mixer or amalgamator prior to placement of the delivery portion or cap thereon. The dentist is assured that the diaphragm or frangible •20 seal will be sufficiently durable so as to avoid any unintentional rupturing of the frangible seal and inadvertent or .4 5 unintentional dispensing of any material contained within the cartridge body. After mixing the dentist places the delivery P-2131 portion or cap onto the reduced diameter end causing the frangible seal to rupture. In another embodiment, the dentist simple removes the twist-off tab and then places the delivery portion or cap onto the reduced diameter end. The dental material can then be conveniently dispensed. The cartridges or capsules may be sold empty or pre-filled with material. The cartridges may also be pre-filled with one component of material, such as a predetermined amount of powder, and a liquid second component that is placed in the cartridge by the dentist. Additionally, the 1 0 frangible seal or diaphragm may be place anywhere along the passage formed in the reduced diameter end or portion as long as roeoo S. a temporary seal is provided. The frangible seal need only be associated with the reduced diameter portion or end. 'O09 Additionally, it should be appreciated that while the present 1 5 invention has particular applicability to dispensing of dental material, any type of material may be utilized with the present invention.

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While several different embodiments of the present invention S have been illustrated and described, it will be obvious to those 2 0 skilled in the art to apply the teachings of the present *4 0 invention. As a result, various modifications may be made without departing from the spirit and scope of this invention.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

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Claims

1. A method for mixing and dispensing a dental material including the steps of: preloading a predetermined amount of a dental material into a dispensing cartridge having a filling end and an opposite discharge and closed by a frangible seal, sealing the filling end of the dispensing cartridge with a displaceable piston after the filling thereof with said dental material, storing the cartridge containing said preloaded dental material until ready for use, removing the displaceable piston prior to using, placing a predetermined amount of a second dental material into said cartridge to be mixed with said first 15 dental material whereby the user may selectively adjust the o ratio of said first and second dental materials, *o replacing the displaceable piston to reseal said filling end of the cartridge, agitating said cartridge to mix said first and second dental materials in situ within said cartridge to form a homogeneous mixture of said first and second materials, fracturing said frangible seal, and S effecting the displacement of said piston to extrude the homogeneous mixture of said first and second dental materials through said discharge end directly where needed.

2. The method as defined in Claim 1 wherein the p~eloading of the first mentioned dental materiaL is a Powder.

3. The method as defined in Cla'.m I wherein the pJ~icenent of said second dental material is a liqi..id.

4. A method at in Claim 1 wherein: the placing of said first dental material is a powder; and. the placing of said second dental material is a l1 liquid.

A method as in Claim 1 wherein the placing of said first dental material is a paste; and the placing of said second dental material is a liquid.

6. A dispensing cartridge for practicing the method de~fined by Claims 2. to 5 wherein said cartridge includes: a body defining a reservoir for receiving a dental material to be dispensed, said body having an open filling end and an oppositely disposed discharge end, said discharge end defining a discharge opening, means forming a frangible seal to seal said discharge opening, a displaceable piston to seal said filling end, said piston having an ear to facilitate grasping said piston for effecting the removal and reinsertion of said piston.

7. A dispensing cartridge as defined in Claim 6 and including a delivery nozzle and means for detachably 0* connecting said delivery nozzle to said discharge end.

8. A dispensing cartridge as defined in Claim 7 wherein said delivery nozzle includes a cannula.

9. A dispensing cartridge as defined in Claim 7 and delivery nozzles having a cannula of varying sizes whereby said delivery nozzles are interchangeably and detachably connected to said discharge end.

A dispensing cartridge as defined in Claims 7 to and including a frangible diaphragm for sealing said discharge opening, said diaphragm having a reduced portion which fractures along said reduced portion when said delivery nozzle is attached to said discharge end.

11. A dispensing cartridge as defined in Claim 6 wherein said means forming a frangible seal includes a sealing cap secured to said discharge end for sealing said discharge opening, and reduced portion adjacent said sealing cap wherein said sealing cap may be readily fractured about said reduced portion co form said discharge opening.

12. A dispensing cartridge as defined in Claim 7 S Swherein said means for detachably connecting said delivery nozzles includes an angled surface defining an exterior shoulder about said discharge opening, and said delivery nozzle having complementary internal ramp surfaces defining a bearing surface arranged to latch said delivery nozzle onto said exterior shoulder of said discharge opening.

13. A method of mixing and dispensing a dental material, said method substantially as hereinbefore described with reference to the accompanying drawings.

14. A dispensing cartridge substantially as hereinbefore described with reference to the accompanying drawings. Dated this 3rd day of July 2002 PATENT ATTORNEY SERVICES Attorneys for CENTRIX, INC S *S *a 5* S S ft f f f